1. Field of the Invention
The present invention relates to an air circuit breaker, and particularly, to an air circuit breaker having a mechanical trip indicating mechanism capable of mechanically reliably indicating a user of a trip operation of the air circuit breaker having done when an overcurrent trip relay sensed a fault current on a circuit.
2. Background of the Invention
In general, an air circuit breaker includes as a controlling unit an overcurrent trip relay (OCR) which senses a fault current on a circuit and then generates and outputs a control signal to allow a trip operation (i.e., automatic circuit breaking) of the air circuit breaker upon the occurrence of such fault current. The air circuit breaker also includes a switching mechanism connected to a movable contactor to drive the movable contactor to switch the circuit to close or open, and an actuator (configured as a solenoid coil actuator, for example) connected to the switching mechanism such that upon receiving a control signal from the overcurrent trip relay, the actuator mechanically transfers the control signal to the switching mechanism to thusly be tripped. Here, since the overcurrent trip relay is implemented as an electronic control circuit, it can store information as to that the control signal is outputted by itself or display (indicate) such information on a display or the like. However, the trip indicating function of the overcurrent trip relay merely denotes that the control signal was outputted for the trip operation. For example, if the actuator has received the control signal but failed to mechanically transfer the control signal to the switching mechanism, the trip indication becomes false. Accordingly, reliability may not be ensured for the electronic trip indicating function of the overcurrent trip relay. Thus, an air circuit breaker having such mechanical trip indicating mechanism according to the present invention is required.
Now, the configuration and operational effect of an air circuit breaker according to one example of the related art will be described with reference to the accompanying drawing.
FIG. 1 is a perspective view showing an overall outer appearance of an air circuit breaker according to the related art. As shown in FIG. 1, an air circuit breaker 1 according to the related art includes a main cover 2 disposed at a front face as a portion serving as an interfacing for as a user manipulation or the like. An overcurrent trip relay 3 is disposed at one side on the main cover 2, and an auxiliary cover 4 for particularly covering the overcurrent trip relay 3 is disposed with being supported on the main cover 2. Manual manipulation buttons for manually switching on or off the air circuit breaker 1 are disposed at a portion of the main cover 2 adjacent to the auxiliary cover 4. Such buttons includes a switch-off button 6 for manually breaking (switching off) the air circuit breaker 1, and a switch-on button 5 for manually closing (conducting) the air circuit breaker 1.
FIG. 2 is a perspective view showing a connection relation among an actuator, a driving force transmitting unit and a switching mechanism all for a trip operation in a state of the front main cover being removed from the air circuit breaker according to the related art. An internal configuration of the related art air circuit breaker will now be described with reference to FIG. 2.
Inside the air circuit breaker having the main cover removed, an actuator 20 adjacent to the main cover 2 (see FIG. 1) is disposed at a rear side of the overcurrent trip relay 3 (see FIG. 1), and an output link 21 corresponding to an output unit of the actuator 20 protrudes through an opening of the side face of the actuator 20 and is vertically movable so as to transfer a mechanical trigger signal. Also, a first link unit 23 is disposed at a side surface of the actuator 20 such that it contacts the vertically lowered output link 21 so as to transfer the vertical driving force to an off shaft 36 of a switching mechanism 30 via a protrusion 22 of the first link unit 23. The switching mechanism 30 is disposed at a rear side of the main cover 2 to be adjacent to the actuator 20. Accordingly, when the off shaft 36 is pressed by the protrusion 22 of the first link unit 23, the switching mechanism 30, in response, applies a driving force to separate a movable contactor from a stationary contactor for tripping a circuit. An unexplained reference numeral 1a in FIG. 2 denotes an insulation molding portion for supporting movable contactors for each phase and corresponding stationary contactors to be electrically insulated by each phase.
FIG. 3 is a perspective view showing the configuration of the actuator and the driving force transmitting unit of the air circuit breaker according to the related art. As shown in FIG. 3, in order for the output link 21 of the actuator 20 to mechanically transfer a trigger signal via the opening at the side surface of the actuator 20, namely, to trigger the switching mechanism 30 to perform the trip operation, the output link 21 protrudes to be vertically movable.
The first link unit 23 is contacted and pressed by the output link 21 which moves in a vertical direction, specifically, moves downwardly in the vertical direction when transferring a mechanical trigger signal, thus to be vertically moved. Accordingly, the off shaft 36 (see FIG. 2) of the switching mechanism 30 is pressed by the first link unit 23 to be then rotated.
Description will be given of the switching mechanism of the air circuit breaker according to the related art and a switching operation of the contact point between a movable contactor connected to the switching mechanism and the corresponding stationary contactor, with reference to FIGS. 4 to 6. Here, although an air circuit breaker according to the present invention is related to a mechanical trip indicating mechanism other than the switching mechanism and the contactors, such switching operation of the contactors can be recited for the understanding of the configuration and operation of the corresponding parts in the air circuit breaker according to the present invention. So the description is introduced herein.
FIG. 4 is a state view showing the operation among a switching mechanism, a movable contactor connected to the switching mechanism, and a stationary contactor in an air circuit breaker according to the related art, which shows an operational state where the air circuit breaker is broken (tripped, blocked) and a closing spring is charged. FIG. 5 is a state view showing the operation among the switching mechanism, the movable contactor connected to the switching mechanism, and the stationary contactor in the air circuit breaker according to the related art, which shows an operational state where the air circuit breaker is closed (conducted) and the closing spring is discharged, and FIG. 6 is a state view showing the operation among the switching mechanism, the movable contactor connected to the switching mechanism, and the stationary contactor in the air circuit breaker according to the related art, which shows an operational state where the air circuit breaker is broken (tripped) and the closing spring is discharged.
Now, a case of manually switching a circuit off in the related art, or a case of automatically breaking (tripping) a circuit by sensing a fault current on the circuit will be described.
As shown in FIG. 5, in case where the air circuit breaker is manually switched off in a closed state, when a user presses the switch-off button 6, an off plate 39 is horizontally moved in a left side in FIG. 5, so as to press the off shaft 36, thereby rotating the off shaft 36.
Alternatively, upon performing an automatic trip operation, the overcurrent trip relay detects a fault current on the circuit, thus to generate and output a trip control signal to the actuator. The actuator then operates in response to the trip control signal. Accordingly, the output link and the first link unit of the actuator cooperate with each other to thusly be moved vertically. As a result, the off shaft 36 of the switching mechanism 30 is pressed by the first link unit to be rotated.
In any of the manual method or the automatic method, once the off shaft 36 is rotated, an open latch 37 is rotated to release a link unit 32. Thus, a closing spring 38, which is tensioned to be charged with an elastic energy in the closed state as shown in FIG. 5, discharges such elastic energy (i.e., returns to initial state shrunk as shown in FIG. 6), whereby a driving lever 51 connected to one end of the closing spring 38 is pulled up to thereby be counterclockwise rotated.
Accordingly, a main shaft 50 is rotated in the counterclockwise direction, and a connection link 52 having one end contacted by the driving lever 51 and the other end connected to the movable contactor 53 is moved to a right side in FIG. 5 so as to pull the movable contactor to the right side. The movable contactor 53 is then separated from an upper terminal 54a corresponding to a stationary contactor as shown in FIG. 6, thereby completing the manual trip operation or automatic trip operation to block the circuit. A lower terminal 54b is always electrically and mechanically connected to the movable contactor 53 by a connection member formed of an electric conductor (not shown).
A case of operating the related art air circuit breaker from an opened state to a closed state will now be described.
The state shown in FIG. 6 is a state where the movable contactor 53 is separated from the upper terminal 54a (i.e., circuit blocked state) but the closing spring 31 is not charged. In order for the movable contactor 53 to be driven to the closed state (i.e., circuit conducted state) in which it comes in contact with the upper terminal 54a, first of all, the closing spring 31 which applies a driving force for driving the movable contactor 53 should be charged as shown in the state of FIG. 4. The closing spring 31 is charged by several methods, for example, by unfolding a folded spring charging handle (no reference numeral given although shown on the main cover 2 of FIG. 1) to manually manipulate a cam shaft (no reference numeral given although shown in FIGS. 4 to 6), by driving a motor (not shown) to operate the cam shaft, and the like.
As such, under the state where the closing spring 31 is charged to thusly be in the state as shown in FIG. 4, when a user presses the switch-on button 5, an ON coupling 35 is rotated clockwise in FIG. 4 to restrict the closing latch 33. Accordingly, the ON shaft 34 maintaining the charged state of the closing spring 31 is pressed to be rotated in a counterclockwise direction, thereby releasing the closing latch 33. The link unit 32 is rotated counterclockwise by the closing spring 31 which discharges the charged elastic energy, thereby rotating the driving lever 51 connected to the link unit 32 in the clockwise direction, whereby the connection link 52 is moved in the left direction in FIG. 4 to allow the movable contactor 53 connected to the connection link 52 to come in contact with the upper terminal 54a corresponding to the stationary contactor, whereby the circuit is conducted (closed), thereby completing the closing operation.
In the related art air circuit breaker having such configuration, the overcurrent trip relay is implemented as an electric control circuit, it can remember (store) that it generated and outputted the control signal or display (indicate) such information on a display or the like.
However, the trip indicating function of the overcurrent trip relay merely denotes that it generated and outputted the control signal for the trip operation. For example, if the actuator received the control signal but failed to operate, it may fail to transfer a mechanical trigger signal to the switching mechanism. As a result, a trip operation is not performed and the trip indicated becomes false, which makes it impossible to ensure a reliability of the electronic trip indicating function of the overcurrent trip relay.